This report describes the histological and immunohistochemical features of a small intestinal tumor that resembled a human gastrointestinal stromal tumor (GISTs) in a seven-year-old male cross-breed dog. This was unique because of the expression of desmin by the tumor. Grossly, the white-gray tumor measured 8.0 × 4.0 × 6.5 cm and was 760 gram in weight. It was cystic and enveloped the jejunum. ...